The delivery of therapeutic agents for the treatment of diseases and other pathological conditions may be accomplished by various means. These include oral, intravenous, subcutaneous, transdermal, intramuscular administration or topical application. For some therapeutic agents, the existing modes of delivery either are unable to deliver sufficient dosages to the disease site without adverse systemic side effects or are unable to allow sufficient retention of the therapeutic product at the disease site for a time sufficient to produce the intended therapeutic effect.
Drugs that prevent or reduce the proliferation of pathological cell types are essential to the treatment and control of various diseases involving undesirable or uncontrolled cell proliferation. But antiproliferatives, by definition, must be toxic to certain cell types. It is often not feasible to administer these drugs systemically, because the amounts needed to control the diseased cell types may be toxic or deadly to the patient's normal cells. This difficulty could be circumvented by administering antiproliferative agents directly to the site of the undesired cell proliferation. A mechanism is also needed for retaining antiproliferative agents at the disease site, so that they may effectively control the proliferation of undesired cells, while being restrained from migrating and damaging normal cell types.
Specific diseases and conditions for which site-specific delivery and retention of anti-proliferatives would be particularly effective are briefly described below. Each of these conditions involves the proliferation of a particular undesirable cell type, and systemic administration of drug therapy for their treatment has not yielded optimal results.